Question

alguém sabe a resposta ?

Answer 1

$\left[\begin{array}{cc}-2&1\\1&-2\\\end{array}\right] * \left[\begin{array}{c}x\\y\\\end{array}\right] = \left[\begin{array}{c}9\\3\\\end{array}\right] = \\ = \left \{ {-2x+y=9} \atop {x-2y=3}} \right. = \left \{ {{-4+2y=18} \atop {x-2y=3}} \right. =-3x=21, portanto, x=-7 \\ =-7-2y=3, portanto, y= -5$

x=-7 e y=-5